How drywall responds to water
A sheet of drywall is a gypsum core faced with paper on both sides. Gypsum tolerates a short wetting reasonably well, and clean, firm drywall that was wet for a short time can often be dried and kept. The paper is the weak point. It absorbs water, loses strength, and gives mold a surface to grow on if it stays wet. Moisture left in building materials can allow mold growth, commonly within a day or two under the right conditions.
Drywall also wicks. Water on the floor climbs the wall through the gypsum core, commonly several inches and sometimes much further, above the level where the floor was wet. The damage visible on the paint is often lower than the real extent inside.
Behind the drywall is insulation, and that matters as much as the board. Fiberglass batts in an exterior wall hold water against the back of the drywall and the framing. Once they're wet, they're rarely worth drying; they're replaced.
What people notice
- Drywall that feels soft or gives slightly when pressed.
- Paint that bubbles, peels or shows a tide-line stain.
- Seams and tape lifting, or screw heads popping through.
- Swollen or crumbling drywall at the bottom edge, just above the baseboard.
- A wall that looks dry but smells musty.
- A wall that bows outward between studs.
Why walls get wet here
Drywall damage is almost always the result of something else: water on the floor from an appliance, a toilet or a water heater; a hidden supply or drain leak inside the wall; a burst pipe in an exterior wall after a cold snap; rain getting past window flashing in a summer storm; or water that has come down from the floor above. In basements, walls get wet from the bottom up, when water on the floor wicks into drywall that was hung tight to the concrete.
In townhouses and condominiums, shared walls add another path. Water crosses from one unit to the next along the floor at the base of a party wall, and those walls are often built as fire-rated assemblies with more than one layer of drywall.
Tell us where the water came from and how long it sat.
Talk to a Restoration ProKeep it or cut it out?
Often dried in place
- Firm drywall wet by clean water for a short time.
- Walls with no insulation, or insulation that stayed dry.
- Walls where the cavity can be dried by air forced through small holes behind the baseboard.
- Moisture-resistant or cement board in bathrooms, if it's still sound.
Usually removed
- Drywall that is soft, swollen, crumbling or sagging.
- Any drywall reached by drain water, bowl water or sewage.
- Drywall with wet insulation behind it.
- Drywall with visible growth on the paper.
- Board that stayed wet for many days before anyone found it.
When drywall does come out, it's usually cut in a straight line, at a set height above the highest wet reading. A clean line makes the rebuild simpler and faster than chasing the stain.
The first hour, and who to tell
Once the source is stopped, the best thing you can do for the walls is get water off the floor, because water on the floor is what keeps feeding the drywall. Pull furniture back, lift rugs, and leave interior doors open so air moves. Keep windows closed in humid weather.
If a shared wall is involved, tell the neighbor and the management office, because the other side may be wet too. Landlords should hear from tenants promptly, even about damp walls that seem minor. Contact your own insurer too; whether anything applies depends entirely on your individual policy and the circumstances.
How drywall water damage is repaired
- Reading the wall. Moisture meters are run up the wall from the floor until readings are normal, and along it past the visible damage. That sets the cut line, if one is needed.
- Removing baseboard and trim. Carefully, so it can usually go back on.
- Deciding the approach. Dry in place, or remove to a line. The decision is based on readings, the water category and the insulation behind.
- Removal. Where needed, drywall is cut in a straight line above the wet readings and removed, along with wet insulation.
- Cleaning. Exposed framing is cleaned, and treated where the water was not clean.
- Drying. Air movers and dehumidifiers dry the studs and bottom plate. Where drywall stays, air is directed into the cavity through small holes behind the baseboard line.
- Confirming dry. Framing is metered until it matches dry references. Nothing is closed up before that.
- Rebuild. New insulation, new drywall, tape, three coats of joint compound with drying time between them, sanding, primer and paint. Texture is matched where the wall has one. Baseboard goes back on.
In basements, drywall is best reinstalled with a small gap above the concrete, hidden by the baseboard. It stops the board wicking water from the slab the next time the floor gets wet.
Plaster, fire-rated walls and bathrooms
Older homes in Arlington and Alexandria, and some older homes elsewhere, have plaster rather than drywall. Plaster is harder and more tolerant of a brief wetting, but it dries slowly and can separate from the lath. It's often dried in place and repaired locally rather than replaced.
Party walls between townhouses, and corridor and demising walls in condominium buildings, are often fire-rated assemblies. When they're opened, they're rebuilt with the same type and number of layers, and the association or building management usually needs to know. In bathrooms, tile walls may be backed by cement board rather than drywall; water behind tile is explained on the hidden wall leak page.
What affects time and cost
The height and length of the damage, whether insulation got wet, the wall finish, and the number of rooms all matter. Drying usually takes a few days. The rebuild takes longer than people expect, because joint compound needs to dry between coats. Smooth painted walls are quicker than textured, plaster or wallpapered walls, and fire-rated assemblies need more material.
The crew prices the work upfront, before anything is cut, with no hidden fees.
Get the cut line, the rebuild plan and the price in one call.
Call for Upfront PricingAfterward
- In basements, keep drywall and baseboard slightly off the slab.
- Choose moisture-resistant board in laundry rooms, bathrooms and around water heaters.
- Keep a little space between furniture and exterior walls so air can move.
- Fix bath fan and window flashing problems that repeatedly wet the same wall.
- If a repaired wall smells musty months later, have it checked with a meter.
Related services
- Leaks behind walls
- Ceiling water damage
- Finished basement cleanup
- Mold remediation
- Townhouses
- Reconstruction and repairs
Drywall water damage: common questions
Can wet drywall be dried instead of replaced?
Often, if it was wet with clean water for a short time, it's still firm, and the insulation behind it stayed dry or there isn't any. Readings and a firmness check decide. Soft, swollen or contaminated drywall is removed.
How high up the wall does it need to be cut?
It depends on how far the water wicked, which meters measure. The cut is usually made in a straight line a little above the highest wet reading. Sometimes that's a foot or two; sometimes more.
Why do they cut the drywall higher than the stain?
Because drywall wicks water upward inside the core, and the stain on the paint is usually lower than the real extent. Cutting to the readings rather than the stain avoids leaving wet material in the wall.
Does wet insulation need to be replaced?
Usually. Fiberglass batts hold water against the framing and the back of the drywall, dry slowly, and lose effectiveness when compressed. Replacing them is simpler and more reliable than drying them.
How soon can I paint after a leak?
Only when the wall has been metered dry. For drywall dried in place, that's commonly a few days after drying starts. For new drywall, after the joint compound has fully dried. Use a stain-blocking primer over any water marks.
The wall between my townhouse and my neighbor's got wet. Who opens it?
Both sides may need to be checked. Let your neighbor and the association know. The crew can dry and assess your side, coordinate with the neighbor for theirs, and make sure a fire-rated wall is rebuilt the way it was built.
My walls are plaster. Is it different?
Yes. Plaster tolerates brief wetting better than drywall but dries slowly and can loosen from the lath. It's usually dried in place, checked for loose areas, and repaired locally rather than torn out.
How long does the whole repair take?
Drying commonly takes a few days. Rebuilding usually takes several more, because joint compound needs time to dry between coats before sanding and painting. Larger areas, texture and plaster take longer.